Mount Sinai School of Medicine, New York, NY; Institute of Hematology and Tumor Biology Research and Department of Hematology, the first affiliated hospital of Wenzhou Medical College, Wenzhou, China; Institute of Hematology and Tumor Biology Research and Department of Hematology, the first affiliated hospital of Wenzhou Medical College, Wenzhou, China; Mount Sinai School Medicine, New York, NY; Department of Environmental Health, University of Cincinnati, Cincinnati, OH

Mount Sinai School of Medicine, New York, NY; Institute of Hematology and Tumor Biology Research and Department of Hematology, the first affiliated hospital of Wenzhou Medical College, Wenzhou, China; Institute of Hematology and Tumor Biology Research and Department of Hematology, the first affiliated hospital of Wenzhou Medical College, Wenzhou, China; Mount Sinai School Medicine, New York, NY; Department of Environmental Health, University of Cincinnati, Cincinnati, OH

Mount Sinai School of Medicine, New York, NY; Institute of Hematology and Tumor Biology Research and Department of Hematology, the first affiliated hospital of Wenzhou Medical College, Wenzhou, China; Institute of Hematology and Tumor Biology Research and Department of Hematology, the first affiliated hospital of Wenzhou Medical College, Wenzhou, China; Mount Sinai School Medicine, New York, NY; Department of Environmental Health, University of Cincinnati, Cincinnati, OH

Mount Sinai School of Medicine, New York, NY; Institute of Hematology and Tumor Biology Research and Department of Hematology, the first affiliated hospital of Wenzhou Medical College, Wenzhou, China; Institute of Hematology and Tumor Biology Research and Department of Hematology, the first affiliated hospital of Wenzhou Medical College, Wenzhou, China; Mount Sinai School Medicine, New York, NY; Department of Environmental Health, University of Cincinnati, Cincinnati, OH

Mount Sinai School of Medicine, New York, NY; Institute of Hematology and Tumor Biology Research and Department of Hematology, the first affiliated hospital of Wenzhou Medical College, Wenzhou, China; Institute of Hematology and Tumor Biology Research and Department of Hematology, the first affiliated hospital of Wenzhou Medical College, Wenzhou, China; Mount Sinai School Medicine, New York, NY; Department of Environmental Health, University of Cincinnati, Cincinnati, OH

Mount Sinai School of Medicine, New York, NY; Institute of Hematology and Tumor Biology Research and Department of Hematology, the first affiliated hospital of Wenzhou Medical College, Wenzhou, China; Institute of Hematology and Tumor Biology Research and Department of Hematology, the first affiliated hospital of Wenzhou Medical College, Wenzhou, China; Mount Sinai School Medicine, New York, NY; Department of Environmental Health, University of Cincinnati, Cincinnati, OH

Mount Sinai School of Medicine, New York, NY; Institute of Hematology and Tumor Biology Research and Department of Hematology, the first affiliated hospital of Wenzhou Medical College, Wenzhou, China; Institute of Hematology and Tumor Biology Research and Department of Hematology, the first affiliated hospital of Wenzhou Medical College, Wenzhou, China; Mount Sinai School Medicine, New York, NY; Department of Environmental Health, University of Cincinnati, Cincinnati, OH

Mount Sinai School of Medicine, New York, NY; Institute of Hematology and Tumor Biology Research and Department of Hematology, the first affiliated hospital of Wenzhou Medical College, Wenzhou, China; Institute of Hematology and Tumor Biology Research and Department of Hematology, the first affiliated hospital of Wenzhou Medical College, Wenzhou, China; Mount Sinai School Medicine, New York, NY; Department of Environmental Health, University of Cincinnati, Cincinnati, OH

Mount Sinai School of Medicine, New York, NY; Institute of Hematology and Tumor Biology Research and Department of Hematology, the first affiliated hospital of Wenzhou Medical College, Wenzhou, China; Institute of Hematology and Tumor Biology Research and Department of Hematology, the first affiliated hospital of Wenzhou Medical College, Wenzhou, China; Mount Sinai School Medicine, New York, NY; Department of Environmental Health, University of Cincinnati, Cincinnati, OH

Mount Sinai School of Medicine, New York, NY; Institute of Hematology and Tumor Biology Research and Department of Hematology, the first affiliated hospital of Wenzhou Medical College, Wenzhou, China; Institute of Hematology and Tumor Biology Research and Department of Hematology, the first affiliated hospital of Wenzhou Medical College, Wenzhou, China; Mount Sinai School Medicine, New York, NY; Department of Environmental Health, University of Cincinnati, Cincinnati, OH

Mount Sinai School of Medicine, New York, NY; Institute of Hematology and Tumor Biology Research and Department of Hematology, the first affiliated hospital of Wenzhou Medical College, Wenzhou, China; Institute of Hematology and Tumor Biology Research and Department of Hematology, the first affiliated hospital of Wenzhou Medical College, Wenzhou, China; Mount Sinai School Medicine, New York, NY; Department of Environmental Health, University of Cincinnati, Cincinnati, OH

Mount Sinai School of Medicine, New York, NY; Institute of Hematology and Tumor Biology Research and Department of Hematology, the first affiliated hospital of Wenzhou Medical College, Wenzhou, China; Institute of Hematology and Tumor Biology Research and Department of Hematology, the first affiliated hospital of Wenzhou Medical College, Wenzhou, China; Mount Sinai School Medicine, New York, NY; Department of Environmental Health, University of Cincinnati, Cincinnati, OH

Mount Sinai School of Medicine, New York, NY; Institute of Hematology and Tumor Biology Research and Department of Hematology, the first affiliated hospital of Wenzhou Medical College, Wenzhou, China; Institute of Hematology and Tumor Biology Research and Department of Hematology, the first affiliated hospital of Wenzhou Medical College, Wenzhou, China; Mount Sinai School Medicine, New York, NY; Department of Environmental Health, University of Cincinnati, Cincinnati, OH

Abstract

Epidemiologic evidence suggests that a diet rich in fruits and vegetables is associated with a reduced risk of prostate cancer (PCa) development. Although several dietary compounds have been tested in preclinical PCa prevention models, no agents have been identified that either prevent the progression of premalignant lesions or treat advanced disease. Momordica charantia, known as bitter melon in English, is a plant that grows in tropical areas worldwide and is both eaten as a vegetable and used for medicinal purposes. We have isolated a protein, designated as MCP30, from bitter melon seeds. The purified fraction was verified by SDS-PAGE and mass spectrometry to contain only two highly- related single chain Type I ribosome-inactivating proteins (RIPs), \#945;-momorcharin and \#946;-momorcharin. RIPs have been shown to inhibit protein synthesis and induce DNA damage. Although the precise mechanism of action of this family of single chain RIPs has not been well delineated, they are known to enter the cell through endocytosis and can induce apoptosis selectively in cancer cells. We demonstrated that MCP30 can also act as a HDAC (histone deacetylase) inhibitor and induce histone (H3 and H4) acetylation in PIN and PCa (LNCaP and PC-3) cell lines, but not in normal human prostate epithelial cells (RWPE-1). In addition, MCP30 inhibited the growth of human PIN and PCa cell lines in vitro by inducing apoptosis via induction of caspase cleavage, with no effect on RWPE-1 cells. We performed an in vivo study which demonstrated that MCP30 significantly suppresses the growth of PC-3 human prostate cancer cells in nude mice. To determine the mechanisms underlying the pro-apoptotic effect of MCP30, we examined the alterations in intracellular signaling pathways induced by MCP30. Real-time PCR and Western blot analysis showed that the two RIPs can induce both mRNA and protein expression of PTEN and KLF6, two known and well-characterized prostate tumor suppressor proteins. This induction was accompanied by decreased Akt phosphorylation leading to increased GSK3\#946; activity. Moreover, we observed that treatment with MCP30 suppresses Wnt/\#946;-catenin activity, as detected by Tcf-luciferase reporter assay and intracellular localization assay (for \#946;-catenin). Finally, MCP30 treatment decreased the expression levels of c-Myc and Cyclin-D1 in PIN and PCa cell lines. Although the direct relationship between RIP-induced DNA/RNA damage and their novel effects on apoptosis and HDAC inhibition is presently unclear, our results suggest that Type I RIPs derived from plants (bitter melon) can be utilized in the prevention and treatment of prostate cancer.